Several studies involving dynamic light scattering techniques have been undertaken in collaboration with scientists at NIH and other research institutions. Recent emphasis has been on developing methods to study the properties of large lattice-like polymer structures. These techniques have been applied, for example, to an examination of fibrin gels and plasma clots in order to assess the effects of subunit crosslinking on the resistance of a clot to proteolytic degradation. Other studies concern the development of shear rigidity in plasma clots, the relationship between molecular structure and the mechanical properties of polyacrylamide gels, and the effects of calcium ions on the conformations of mucin glycoproteins. Assistance has been given to other research projects for which it has been important to obtain information about the size of particles in laboratory samples. Notable among these is an investigation of the efficacy of protocols for preparing "coated vesicles" from brain tissue. We continue to provide supporting services for the development of laser Doppler bloodflow instrumentation and other devices utilizing quasi-elastic light scattering.